Field of the Invention
The present invention relates to a flat panel display, and more particularly to a flat panel display and a fabricating method thereof that are adapted for conducting a patterning process without using a photo process, thereby reducing its process time and minimizing pattern defects.
Discussion of the Related Art
Display devices are becoming increasingly important for visual information communication. Cathode ray tubes (CRTs), or Braun tubes, which are popular display devices have problems of weight and large size.
A flat panel display that includes a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), or an electro-luminescent (EL) display have also been commercialized.
The liquid crystal display has been replacing the CRT rapidly in various applied fields because it can satisfy the need for light weight, and thin physical profile.
In particular, an active matrix type liquid crystal display, which drives liquid crystal cells using a thin film transistor (hereinafter, referred to as “TFT”), has an advantage that its picture quality is good and its power consumption is low. TFT LCDs have been rapidly developed to larger sizes and higher resolutions due to improvements in mass production technology and the fruitful result of research and development.
The active matrix type liquid crystal display as illustrated in FIG. 1 includes a color filter substrate 22 and a TFT array substrate 23 bonded together with a liquid crystal layer 15 therebetween. The liquid crystal display illustrated in FIG. 1 represents part of the whole effective picture area.
The color filter substrate 22 includes a black matrix (not illustrated), a color filter 13 and a common electrode 14 on the rear surface of an upper glass substrate 12. A polarizer 11 is stuck to the front surface of the upper glass substrate 12. The color filter 13 inclusive of red (R), green (G) and blue (B) color filters transmits a visible ray of light in a specific wavelength range to enable color display.
In the TFT array substrate 23, data lines 19 and gate lines 18 cross each other on the front surface of a lower glass substrate 16. TFT's 20 are formed at these crossings. A pixel electrode 21 is formed at a cell area between the data line 19 and the gate line 18 on the front surface of the lower glass substrate 16. The TFT 20 responds to a scanning signal from the gate line 18 to switch a data transmission path between the data line 19 and the pixel electrode 21, thereby driving the pixel electrode 21. A polarizer 17 is attached to the rear surface of the TFT array substrate 23.
The liquid crystal layer 15 controls the amount of transmitted light incident through the TFT array substrate 23 by an electric field applied thereto.
The polarizers 11 and 17 attached to the color filter substrate 22 and the TFT substrate 23 transmit the light polarized in one direction. The polarizing directions thereof cross perpendicularly when the liquid crystal 15 is in a 90° TN mode.
An alignment film (not illustrated) is formed on the opposite surfaces of the liquid crystal of the color filter substrate 22 and the array TFT substrate 23.
A method for fabricating the active matrix type liquid crystal display is divided into, for example, a substrate cleaning process, a substrate patterning process, an alignment film forming/rubbing process, a substrate bonding/liquid crystal injecting process, a mounting process, an inspection process, and a repair process. The substrate cleaning process removes the impurities contaminating the substrate surface of the liquid crystal display with a cleansing solution. The substrate patterning process is divided into a patterning process of the color filter substrate and a patterning process of the TFT array substrate.
In the alignment film forming/rubbing process, the alignment film is spread over each of the color filter substrate and the TFT array substrate. The alignment film is rubbed with a rubbing cloth. In the substrate bonding/liquid crystal injecting process, the color filter substrate and the TFT array substrate are bonded and a liquid crystal and a spacer are injected through a liquid crystal injection hole. Then, the liquid crystal injection hole is sealed with a sealant.
The mounting process connects a tape carrier package (hereinafter, referred to as “TCP”), on which integrated circuits such as a gate drive integrated circuit and a data drive integrated circuit are mounted, with a pad part of the substrate. The drive integrated circuit may be directly mounted on the substrate by a chip on glass COG method in addition to a tape automated bonding method using the foregoing TCP. The inspection process includes an electrical test carried out after the pixel electrode and the signal lines such as the data line and the gate line are formed in the TFT array substrate; and an electrical test and a macrography carried out after the substrate bonding/liquid crystal injecting process. In the repair process, a restoration is carried out on the substrate judged to be possible to be repaired by the inspection process. In the inspection process, the un-repairable substrates are disposed as wastes.
In the fabricating method of most flat panel displays including the liquid crystal display, a thin film material deposited on the substrate is patterned in a photolithography process. The photolithography process is a series of photographic processes generally including the spread of photo-resist, a mask aligning, an exposure, a development and a cleansing. However, the photolithography process has problems in that the time required for its completion is long, too much of the photo-resist material and the stripping solution are wasted, and it requires expensive equipment like exposure equipment.